AI 中文总结
该研究通过二维p+ip超流体耦合强度瞬时淬火后的QFI，发现非平衡态QFI可区分三种动力学相、编码淬火前拓扑，增强了QFI的诊断能力。
AI 中文摘要
量子费舍尔信息（QFI）被广泛用于表征量子相和量子相变，但其诊断能力有时依赖于基于底层物理先验知识选择特殊的生成器。我们通过研究二维p+ip超流体在耦合强度瞬时淬火后的长时间渐近态的QFI，探究是否可以在非平衡系统中放宽这一要求，采用大子广延子系统内的粒子数作为生成器。在平衡态下，基态QFI在弱配对BCS相和强配对BEC相之间的拓扑相变处连续，未显示出相变的直接特征。然而，淬火后，同一生成器对应的QFI可区分三种动力学相，并能编码淬火前态的拓扑性质。在具有消失序参量的I相，QFI傅里叶谱包含由非平衡分布函数决定的单个零频峰；在具有恒定非零序参量的II相，QFI谱包含零频峰和由最小渐近准粒子能量设定的能隙分隔的两个连续谱，连续谱的边缘行为揭示该最小能量出现在零动量还是有限动量处，若为前者，谱权重在边缘处消失，连续谱内部的符号为大子系统编码淬火前拓扑；在具有时间周期序参量的III相，QFI谱在振荡频率的整数倍处呈现离散峰，同时包含与Floquet准能谱相关的连续谱。我们的结果表明，驱动系统偏离平衡可增强QFI对标准物理可观测量的诊断能力，揭示平衡态下无法获取的信息。
英文摘要
The quantum Fisher information (QFI) is widely used to characterize quantum phases and transitions, but its diagnostic power sometimes relies on selecting special generators based on prior knowledge of the underlying physics. We ask whether this requirement can be relaxed in nonequilibrium systems by studying the QFI of the long-time asymptotic state of a two-dimensional p+ip superfluid following an instantaneous quench of the coupling strength, using the particle number within a large subextensive subsystem as the generator. In equilibrium, the ground-state QFI is continuous across the topological transition between the weak-pairing BCS and the strong-pairing BEC phases, showing no direct signature of the transition. After the quench, however, the QFI associated with the same generator distinguishes the three dynamical phases and can encode the topology of the pre-quench state. In phase I, with a vanishing order parameter, the QFI Fourier spectrum consists of a single zero-frequency spike determined by the nonequilibrium distribution function. In phase II, with a constant nonzero order parameter, the QFI spectrum contains a zero-frequency spike and two continua separated by a gap set by the minimum asymptotic quasiparticle energy. The continuum edge behavior reveals whether this minimum occurs at zero or finite momentum. In the former case, the spectral weight vanishes at the edge, with the sign just inside the continuum encoding the pre-quench topology for large subsystem. In phase III, with a time-periodic order parameter, the QFI spectrum exhibits discrete peaks at integer multiples of the oscillation frequency, together with continua associated with the Floquet quasienergy spectrum. Our results show that driving the system out of equilibrium can enhance the diagnostic power of the QFI for a standard physical observable, revealing information inaccessible in equilibrium.
Comments16 pages, 6 figures
